| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 329 | 5 | 5 | 100% |
| Alpine | - | - | - | - |
| Amador | 2 | - | - | - |
| Butte | 45 | 9 | - | - |
| Calaveras | 7 | - | - | - |
| Colusa | 8 | 3 | - | - |
| Contra Costa | 306 | 20 | - | - |
| Del Norte | - | - | - | - |
| El Dorado | 48 | 11 | - | - |
| Fresno | 90 | 6 | 3 | 50% |
| Glenn | 6 | - | - | - |
| Humboldt | 10 | - | - | - |
| Imperial | 3 | - | - | - |
| Inyo | - | - | - | - |
| Kern | 31 | 4 | 1 | 25% |
| Kings | 15 | - | - | - |
| Lake | 12 | 5 | - | - |
| Lassen | - | - | - | - |
| Los Angeles | 464 | 47 | - | - |
| Madera | 8 | 2 | - | - |
| Marin | 46 | 1 | - | - |
| Mariposa | - | - | - | - |
| Mendocino | 4 | - | - | - |
| Merced | 26 | 3 | - | - |
| Modoc | - | - | - | - |
| Mono | 1 | - | - | - |
| Monterey | 22 | 2 | - | - |
| Napa | 21 | 5 | - | - |
| Nevada | 21 | 1 | - | - |
| Orange | 216 | 43 | - | - |
| Placer | 143 | 44 | - | - |
| Plumas | 3 | - | - | - |
| Riverside | 115 | 29 | - | - |
| Sacramento | 479 | 150 | - | - |
| San Benito | 4 | 1 | - | - |
| San Bernardino | 76 | 16 | - | - |
| San Diego | 278 | 84 | 4 | 5% |
| San Francisco | 50 | 1 | - | - |
| San Joaquin | 116 | 29 | 2 | 7% |
| San Luis Obispo | 38 | 4 | - | - |
| San Mateo | 355 | 104 | - | - |
| Santa Barbara | 31 | 12 | - | - |
| Santa Clara | 507 | 74 | 7 | 9% |
| Santa Cruz | 59 | 20 | - | - |
| Shasta | 11 | 2 | - | - |
| Sierra | 1 | - | - | - |
| Siskiyou | 3 | - | - | - |
| Solano | 83 | 9 | - | - |
| Sonoma | 88 | 5 | - | - |
| Stanislaus | 107 | 5 | - | - |
| Sutter | 10 | 2 | - | - |
| Tehama | 8 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 40 | 12 | 4 | 33% |
| Tuolumne | 4 | - | - | - |
| Ventura | 86 | 6 | - | - |
| Yolo | 135 | 18 | - | - |
| Yuba | 13 | 6 | - | - |
| State Totals | 4584 | 800 | 26 | 3% |
* Birds in a die-off are not included in reported totals because the deaths are not related to WNV. A die-off is defined as a group of 10 or more same species dead birds unless the species is American Crow.
Source: Vector-Borne Disease Section, California Department of Public Health